Slab-rossing machine



rah-71- Aug. 18,, 1959 H, DURANT 2,899,993

SLABROSSING MACHINE Filed June 25, 1956 3 Sheets-Sheet 1 INV EN TOR.

BY JnHDuranf I Aug. 18, 1959 Filed June 25, 1956 J. H. DURANT SLAB-ROSSING MACHINE 3 Sheets-Sheet 2 INVENTOR. John H.Dur'a n 2' Aug. 18, 1959 Filed June 25, 1956 J. H. DURANT SLAB-ROSSING MACHINE S Sheets-Sheet 3 INVENTOR. John HDur-cz n l United States Patent SLAB-ROSSING MACHINE John H. Durant, Portland, Oreg., assignor to Lloyd J Ruble, Eugene, Oreg.

Application June 25, 1956, Serial No. 593,444

4 Claims. (Cl. 144-208) This invention is directed to an improved method and means for recovering the usable wood from slabs developed in milling operations. In the past, said slabs have been considered to have negligible commercial value and have thus been used either as fuel or have been burned as trash. In recent years, log prices have increased and pulp and hardboard chips have been in such short supply that the woody portions of the slabs have substantial commercial value, and many efforts have been made to remove the bark from the logs so that the slabs that are removed in producing lumber may be formed into chips. It is essential that substantially all of the bark be removed in order to qualify said chips for the pulp and hardboard chip market. Many efforts have been made to remove the bark from whole logs. The bark varies in thickness, the slabs vary both in thickness and width, the slabs also have varying degrees of curvature, depending upon the diameter of the logs from which they have been cut, and the peri heral surface of the logs from which said slabs have been cut frequently have burls, knots, and limbs protruding from the peripheral sweep, which makes the debarking or rossing operation difiicult.

One of the principal objects of my invention is to provide a method and means for feeding said slabs of barkcovered lumber past a series of cutting blades, with the fiat side of the slab lying against a plane table and the curved bark-covered periphery arranged uppermost so that cutters may conform the slab to its general outline by removing the bark without removing any substantial portion of the wood.

A further object of my invention is to provide a machine of this character with adjustable cutting means, hold-down means, and guiding means, so that it is readily and quickly adaptable to slabs of any Width, thickness, or

curvature.

A further object of my invention is to provide a rossing machine and a method of debarking slabs which is capable of handling slabs of uneven surface contour and uneven thickness of bark.

A further object of my invention is to provide a machine and a method of practicing my invention which involves simple structures, easy manipulations, and inexpensive equipment of high output, so that the debarked slabs may thereafter be cut into chips and sold competitively on the open market.

Other and further details of my invention are hereinafter described with reference to the accompanying drawings, in which: i

Fig. 1 is a plan View of a machine embodying my invention, showing the manner in which slabs are guided and debarked by being moved endwise through said machine; j v

Fig. 2 is a transverse section through said machine, taken on the line 22 in Fig. 1, illustrating the manner in which the mechanism is adapted to conform to the peripheral sweep of a slab as it is fed through said machine;

Fig. 3 is a sectional view taken on the line 3-3 in 2 1 Fig. 1, illustrating the manner in which said slabs are held to a plane top table or rails and conveyed endwise through said machine, said figure showing the hold-down rollers, which not only hold the slab to a table, but also guide it endwise without requiring lateral guide elements; Fig. 4 is a more or less schematic view of a pair of associated cutting heads set to remove bark from a slab which passes beneath them, said schematic view being taken substantially on the line 2--2 in Fig. l; and

Fig. 5 is a view similar to Fig. 4, illustrating the adjustment .by which slabs of shorter sweep or smaller diameter may be accommodated, and the cutting heads may be adapted to conform to the peripheral outline of the barkline of said slabs.

A machine embodying my invention is mounted upon a frame 1, upon which is centrally mounted a pair of structural members 2, shown in Fig. 2 as a pair of I beams or other structural members. Carried by said structural members is a table or rails 3, whose upper surface is defined by spaced stringers 4-. Lying intermediate said stringers and exteriorly thereof is a feed chain 5. The plane of the upper course of the endless feed chain and said stringers coincide, as is shown in said Fig. 2. Said plane constitutes a surface over which a slab 6 is guided. Said slab has a plane underface 6a and a curved upper peripheral surface 6b, from which bark 6c is to be removed. Said slab is moved endwise over said table by engagement with upstanding spikes 5a standing upright from the feed chains 5. Said pins are forced into the underface 6a of the slab 6 and prevent lateral movement of said slab. Said feed chains are carried by sprockets 7, which are carried by a pair of spaced journaled shafts 8 supported at their ends by bearings 9 carried by the structural members 2. Said feed chain is of endless form and extends a distance longi- V tudinally, as is shown in Fig. 1, sufficient to accommodate proper feeding to the debarking mechanism and off-bearing therefrom.

Supports 12 lie at opposite sides of said feed chain 5 and are mounted upon the frame 1. Said supports are made of structural members and define guideways 13 for crossheads 14. A crosshead in each support has a section as shown in Fig. 1. Two pairs of opposed flanges 12a face inwardly, and each of the crossheads is provided with four clips 14a, one of which lies exteriorly of a flange and encircles the margin of said flange. This, together with the body of the crosshead, defines a complementary groove with the profile of the flange lying therein, and keeps the crosshead running along a true, straight, vertical pathway up and down the support 12 in which it is located.

Movement of each crosshead is effected by a threaded stem 15 fixed to the crosshead and extending through a horizontal channel 12b forming a part of said support. Above said channel is a miter gear 16 in mesh with a miter pinion 17. Said miter gear 16 is tapped, and this tapped bore is in threaded engagement with the stem. The miter pinion is fixed to an adjusting shaft 18 turned by a crank 19. Thus, as the crank is turned in one direction, it turns the miter gear 16 through the miter pinion 17, and this feeds the stem lengthwise of the guideway 13. Rotation of the crank in the opposite direction lying the table, a cutting head 22 is carried, and at the opposite end of said arm, a motor 23 is secured. The cutting head is driven by a shaft 24 joined to the rotor of the motor 23. .The end of the shaft 24 carrying the cutting head is journaled in laterally extendingboxes 2525a The pivoted arms 21 are rotated about their 3 trunnions, respectively, by a piston-and-cylinder element 26. One end of the cylinder is joined by ears 27 to a lug 27a extending laterally from the support 12. An outer end of a piston rod 26a carries a shackle 28 which engages a'pin 28a fixed to the arm 21. Thus, as the piston-and-cylinder element is retracted, it rotates the pivoted arm upwardly away from the table 3, and as it is extended, it moves the arm and the cutting head carriedthereby toward said table. The piston is of the double-acting type, and receives operating fluid selectively through conduits 26b from a supply under pressure (not shown).

Overlying the feed chain 5 are pairs of conico-frustum rollers 29, which engage the bark-covered upper surface ofv slab 6 as it moves toward the pair of cutting heads 22. Said rollers push the slab downwardly on spikes 5a and hold said slab tightly against the surface of the table 3. Due to the conic periphery of said rollers, they also tend to hold said slab in longitudinal alignment with the table and with the feed chains 5 associated therewith.

Thus, no marginal or lateral guides are needed for a slab, and the conico-frustum rollers coact with the spikes 5a and the arcuate surface of the slab to hold it to movement in a straight line. Said rollers are carried by the free ends of levers 30 pivotally carried by a fixed mount 31 which spans table 3 and provides pivotal mounts for the two roller-supporting arms at the opposite sides peripheral surfaceof said rollers 29 and impaling of theof the table. The other ends of said levers 30 are joined I together by a piston-and-cylinder element 32, which moves said rollers tightly against the bark-covered upper faceof slab 6 when extended, and lifts said rollers out of engagement with the curved peripheral surface 6b of said slab when retracted. Air under pressure is supplied selectively to conduits 32a from a supply (not shown).

The cutting heads 22 are concave in outline, as is shown in Fig. 2, and are of the so-called Yo-yo type. The curvature or sweep, or the degree of concavity, of said cutting heads is predetermined to an optimum sweep of slabs to be debarked. Likewise, the slope of theconicofrustum roller 29 is adjusted to said optimum sweep of the slab. Said cutting heads overlap somewhat, as is shown in Figs. 2, 4- and 5. If a slab is cut from a tree of large diameter, the angle x as shown in Fig. 4 is quite' acute, and the degree of overlap of said cutterheads is substantial. If the cutterheads are set to debark a slab of shorter sweep, that is, one cut from a log of smaller diameter, said angle 2: is larger, as is shown in Fig.15. This change in angle of the cutterheads is ac complished by moving the crossheads 14 longitudinally of the support 12. This moves the trunnion 20 upon which said arms are mounted, upwardly or downwardly with respectto the plane of the table 3. The higher the crossheads are moved on the supports 12, the more acute is the an le x. Thus, as is shown in Figs. 4 and 5, the concavity of the cutting profile may be adjusted to coincide with the peripheral sweep of the wood underlying the bark, and, by proper adjustment, the bark may be cut away or rossed from the wood without cutting away the wood itself, and thus the wood is left free of bark in substantially its entirety, and said slab is usable for making pulp or hardboard chips. The portions of bark removed from a slab fall through the frame into a funnelshaped slot 1a in the frame, as is shown in Fig. 2.

' 1f slabs 6 are fed to a machine embodying my invention, and said slabs have knots,,burls, or other 'protuberanceswhich lie beyond therperipheral sweep of the bark, these portions will normally be cut away with the bark by. the action of thecutting heads 22. Inasmuchas the rollers 29 lie in-advance of the cutting heads, it is necessary that theyride. over I such. a protuberance without relaxing their pressure upon the slabgoing through said machine. '7 As is shown in Fig.1, the cutting heads are arranged in pairs, but they are not axially-aligned; Thus, one

cuttinglhead removes bark slightly in advance .:of the other. This permits said cutting head to overlap, as has been explained and as is illustrated in Figs. 4 and 5, to permit them to be adjusted to remove bark from slabs having diifering peripheral bark-covered surfaces. Said adjustment may easily be made by use of the crank 18, because the arm associated therewith has its pivot point arranged substantially at the center of mass of the motor 23, shaft 24, and cutting head 22. The angular adjustment about the trunnion 20 maybe made through the piston-and-cylinder element 26 by means of appropriate controls. Said piston-and cylinder element 26 will hold the arm in substantially set position.

The method by which elongated slabs of wood are debarked, and the operation of a machine used in connection therewith, involve the following steps:

Slabs are placed upon the infeed chain 5 from a point below the portions of the machine indicated in Fig. 1, and they are aligned generally with the feed chains 5 and impaled upon the spikes 5a carried by said feed chains. When the end of the slab reaches a position underlying the oonico-frustum rollers 29, it may be adjusted slightly to midline and held-there due to the slope of the spikes 5a. This causes the slab to be passed under the cutting heads at their midpoint so that said cutting heads will cut away a more or less continuous out upon a true sweepwhich' corresponds generally to the cambium layer of the slab beneath the bark 6c thereof. Although the cutting heads and their arms are adjustable to various sweeps, it is my experience that little adjustment is needed because most slabs, particularly those developed from Dogulas fir logs, correspond generally in curvature and sweep, and operating time is conserved by running them under the cutter knives at an optimum setting. Unusually thin slabs, or unusually thick ones, require some adjustment, and this may be done either by use of the piston-and-cylinder elements 26, or the crank or other ad? justing'rnechanism, or by a combination of both. Al-

though I illustrate the setting for the crosshead as being.

made through a hand crank, it is to be understood that this this adjustment, and my invention is not to be limited to such specific means.

As the slab passes from under the cutting heads 22, it will have been debarked and cut to a more or less continuous'sweep, the feed chain 5 then conveying it endwise from the machine.

The slab is always arranged with its plane face down andresting upon the table, and with its curved peripheral surface up, for having the bark removed therefrom. The engagement of the flat or plane face of the slab,'the plane face of the table, and the spikes Saof the feed chain 5 associated therewith cause the slab to move along smoothly in a straight line and without intern ruption, and produces a smooth, uniform cut as'it passes beneath" the cutting heads 22.

I claim:

1. A slab-debarking machine that feeds an elongated slab of wood endwise therethrough, each slab having a plane surface and an opposed bark-covered surface of curved peripheral outline, said machine being proportioned and arranged to remove such bark, said machine comprising, a plane slab-supporting table,- a conveyor associated. therewith for engaging a slab to be debarked and to move it endwise over said table with. the plane face of such slab bearing upon said table, a pair of powerdriven, rotary, concave cutting heads offset from each other in the direction of feed of a slab and presenting cutting edges corresponding generally to H e peripheral outline of a slab to be debarked, a pair of upstanding supports, onelying at each side; of said table, and each defining a vertical way, vertically adjustable crossheads carried by said supports, and each being'slidably mounted in the way thereon, a threaded stern mounted on'said crosshead, a gear threaded on said stern, means forq rotating said gear for moving and fixing each of said crossheads along and relatively with respect to its support and the way defined thereon, a pivotal arm carried by each orosshead, one of said cutting heads being carried by one end of said pivotal arm, and a motor operatively joined to said cutting head and carried by the other end of said arm.

2. A slab-debarking machine that feeds an elongated slab of wood endwise therethrough, each slab having a plane surface and an opposed bark-covered surface of curved peripheral outline, said machine being proportioned and arranged to remove such bark, said machine comprising, a plane slab-supporting table, a conveyor associated therewith for engaging a slab to be debarked and to move it endwise over said table with the plane face of such slab bearing upon said table, a pair of powerdriven, rotary, concave cutting heads offset from each other in the direction of feed of a slab and presenting cutting edges corresponding generally to the peripheral outline of a slab to be debarked, a pair of upstanding supports, one lying at each side of said table, and each defining a vertical way, vertically adjustable crossheads carried by said supports, and each being slidably mounted in the way thereon, a pivotal arm having one of said cutting heads carried by one end of said pivotal arm, a motor operatively joined to said cutting head and carried by the other end of said arm, and a motor means connected to said arm and its associated support, urging said arm and its associated cutting head toward said table.

3. A slab debarking machine that feeds an elongated slab of wood endwise therethrough, each slab having a plane surface and an opposed bark-covered surface of curved peripheral outline, said machine being proportioned and arranged to remove such bark, said machine comprising a plane slab-supporting table, a conveyor associated therewith for engaging a slab to be debarked and to move it endwise over said table with the plane face of such slab bearing upon said table, tapered holddown rollers for engaging the bark-covered surface of such slab and holding it firmly against said table, said rollers tapering toward their free ends and being arranged in a mated pair, each subtending an oblique angle to the plane of said table, the angles of said paired rollers opposing each other and extending tangential to the peripheral outline of a slab, thereby restraining a slab being fed to a fixed path lengthwise of said table, a pair of power-driven, rotary, concave cutting heads, oifset from each other in the direction of feed of a slab and presenting cutting edges corresponding generally to the peripheral outline of a slab being debarked, and a pair of mated roller-supporting arms pivotally mounted at opposite sides of said table, each carrying a hold-down roller at one end.

4. A slab-debarking machine that feeds an elongated slab of wood endwise therethrough, each slab having a plane surface and an opposed bark-covered surface of curved peripheral outline, said machine being proportioned and arranged to remove such bark, said machine comprising a plane slab-supporting table, a conveyor associted therewith for engaging a slab to be debarked and operable to move it endwise over said table with the plane face of such slab bearing down on said table, a

pair of power-driven, rotary, concave cutting heads oli-- set from each other in the direction of feed of a slab and presenting cutting edges corresponding exactly to the peripheral outline of wood underlying such bark, and plural hold-down rollers for engaging the barkcovered surface of such slab and holding such slab firmly against the table and guiding such slab along a fixed path extending lengthwise of said table, each of said holddown rollers being conico-frustum with the end of greater diameter thereof being arranged in superimposed relation to the lateral margins of the table.

References Cited in the file of this patent UNITED STATES PATENTS 941,751 Anderson Nov. 30, 1909 1,673,265 Pangborn June 12, 1928 1,851,156 Calahan Mar. 29, 1932 1,956,653 Onstad May 1, 1934 2,005,799 Nicholson et al. June 25, 1935 2,749,952 League June 12, 1956 2,794,465 Gyllenberg June 4, 1957 2,821,220 Nicholson Jan. 28, 1958 FOREIGN PATENTS 921,833 Germany Dec. 30, 1954 

